1. Field of the Invention
The present invention relates to a motion vector detection circuit and an object tracking camera device utilizing the motion vector detection circuit. More specifically, the present invention relates to a motion vector detection circuit which may be utilized in a video camera automatically tracking an object, for example, and an object tracking camera device utilizing the motion vector detection circuit.
2. Description of the Prior Art
As an object tracking technique in taking an object which moves within a screen by a camera, there was a technique which utilizes color information. In such a technique, the color information is detected from an image signal within a designated detection block, and the color information is utilized to determine a target object by registering the color information as a specific color. However, in the prior art, in a case where a color existing in a small area of the object accidentally enters the designated detection block and the color occupies the most of an area of the detection block, the specific color to be registered is largely affected by an influence of the color existing in the small area rather than a color being representative of the object. Therefore, it was difficult to track the object on the basis of the specific color.
Furthermore, another object tracking technique is disclosed in, for example, Japanese Patent Application Laying-Open No. 4(1995)-354490. In this prior art, a specific color is designated as a target, and by detecting the specific color from the image signal, the object is tracked. However, in the prior art, it is required to satisfy an assumption that two or more bodies having the same color as the target color do not exist within the screen, and therefore, in a scene where a plurality of bodies having the same color exist, there was an occasion that the object can not be tracked effectively.
Furthermore, other object tracking technique is disclosed in, for example, Japanese Patent Application Laying-Open No. 61(1986)-9084. In this prior art, color information included in an image signal of the designated detection block is stored, and the object is tracked by renewing the stored color in accordance with an environment of the object. However, in the prior art, since the stored color is renewed at every timing that the environment of the object is changed, the stored color becomes a color different from the color of the object if the stored color is changed many times, and therefore, there was an occasion that it becomes difficult to track the object being targeted.